Elsevier

Landscape and Urban Planning

Volume 71, Issue 1, 28 February 2005, Pages 29-34
Landscape and Urban Planning

Guidance for noise reduction provided by tree belts

https://doi.org/10.1016/j.landurbplan.2004.01.005Get rights and content

Abstract

The effects of noise reduction of six tree belts were examined. An amplifier was placed in front of each tree belt, while a noise meter was placed at various heights and distances behind the tree belt. Net noise reduction effect termed as “relative attenuation” was obtained by subtracting the sound pressure level at each measurement site behind the tree belt from the sound pressure level at equal distances over open ground. Five parameters, including visibility, height, and width of the tree belt, height of receiver and noise source, and the distance between noise source and receiver, were studied. A multiple regression model demonstrating the order of importance of the five parameters in relation to relative attenuation was developed. The five parameters were then transformed into three-dimensionless parameters, i.e., h′: receiver and noise source height/tree height, d′: distance between noise source and receiver/tree height, and m′: belt width/visibility. By plotting the relative attenuation on the coordinate axis of h′, d′ and m′ and curve fitting, a three-dimensionless map of noise reduction by tree belts was formed. The map can be used as guidance in designing three belts for noise reduction in environmental planning.

Introduction

Tree belts situated between the noise source and the receiver can reduce the noise level perceived by the receiver (Kragh, 1979). Wide tree belts which exceed 30 m could reduce the noise by 4–8 dB A (Eyring, 1946, Reethof, 1973, Cook and Haverbeke, 1974). While a wide belt of sparse trees may reduce the noise effectively, it may not be always practical in landscape design. In order to investigate the effect of noise reduction by narrow tree belts, six dense and narrow tree belts were chosen and the noise reduction effect behind them was studied. Parameters such as visibility in the tree belt (visibility), tree height, belt width, receiver and noise source height, and the distance between noise source and receiver (distance) were included in the observations. Then the above parameters were transformed into three-dimensionless parameters to interpret the effect of noise reduction. Finally, a map showing the relationships between the three-dimensionless parameters and the effectiveness of noise reduction were constructed.

Section snippets

Materials

Six kinds of tree belts which are common as hedges in Taiwan were chosen for the study. They were grown on flat areas. The ambient noise was maintained at 48±2 dB A. Each tree belt exceeded 50 m in length beyond which belt length has no effect on noise reduction according to Fang and Ling (2003). The characteristics of the six tree belts are shown in Table 1.

Experimental design

A centerline was drawn perpendicular to the length of the tree belt (Fig. 1). Two transecting lines, A and B, one on each side of and 2.5 m

Typical distribution of relative attenuation

The relative attenuation at various measuring sites of the six tree belts had a similar distribution pattern. Choosing a tree belt of Casuarina equisetifolia as an example, the lower the receiver and noise source height, the greater the noise attenuation (Fig. 2). A turning point existed at a distance approximately 40 m. The relative attenuation declined slowly with increasing distance up to the turning point, but declined rapidly beyond the turning point.

Multiple regressive model

The standardized coefficient (Beta) in

Discussion

When a noise meets a barrier, a noise shadow zone appears behind the barrier. The noise attenuation is high inside the shadow zone, but it is lower outside the shadow zone (Beranek and Vèr, 1992). Therefore, a receiver in the shadow zone can detect a noise reduction effect. The turning point (Fig. 2) found in this study should represent the edge of the noise shadow zone.

Tree height and belt width had positive relationships and visibility had a negative relationships with relative attenuation (

References (7)

There are more references available in the full text version of this article.

Cited by (129)

  • Assessing the social equity of urban parks: An improved index integrating multiple quality dimensions and service accessibility

    2022, Cities
    Citation Excerpt :

    Each season is calculated separately, and the average of the four seasons is used. Although the maximum result is a score of 4, which is higher than other elements, this makes sense because noise reduction, heat island mitigation, air purification, and restoring capacities are all associated with vegetation coverage (Bowler et al., 2010; Cohen et al., 2014; Fang & Ling, 2005; Tyrväinen et al., 2014; Van Renterghem, 2018). Another issue related to the use of the NDVI is the negative score for water surfaces (lakes, rivers, oceans).

  • Effects of street orientation and tree species thermal comfort within urban canyons in a hot, dry climate

    2022, Ecological Informatics
    Citation Excerpt :

    Four of these parameters are influenced by the urban environment, and two parameters are individual choices (Arens and Bosselmann, 1989; Kim and Brown, 2021b; Mazhar et al., 2015). Plants are one of the influential factors in controlling climatic conditions that lead to reduced noise levels (Fang and Ling, 2005; Gachkar et al., 2021),lower stress (Kondo et al., 2019) and reduction in the effect of UHI (Kabano et al., 2021; Wang et al., 2021a). Plants also play an enormous role in improving air quality (Robert D Brown and Gillespie, 1995; Eisenman et al., 2019; Gómez-Moreno et al., 2019) and social interactions in the urban environment (Jennings and Bamkole, 2019).

View all citing articles on Scopus
View full text